Lustering leather



Patented Oct. 13, 1931 UNITED STATES PATENT OFFICE GEORGE E. PENSEL ANDSVEN H. FBIESTEDT, OF AMSTERDAM, NEW YORK, ASSIGNOBS T BITTER CHEMICALCOMPANY, OF AMSTERDAM, NEW YORK, A CORPORATION OF NEW YORK 1T0 Drawing.

' This invention relates to the manufacture of lustrous dyed or undyedleather having a nap, and especially to the treatment of formaldehyde orchrome tanned leather having 5 a nap, such for example as suede or mochaleather.

It is well known that if woolis treated with available chlorine itacquires a luster and feel very similar to silk, and it loses itsfelting properties, but it also ac uires a greater affinity fordyestuffs (see anual of Dyeing by Knecht, Rawson and Loewenthal, Griffin& Company, London, second edition, 1910, pages 56, 57 and 58).

We discovered that the raw skin might be treated with availablechlorine, for example, before the chrome tannage, after it has passedthrough the usual beam shop process, for the removal of the hair, suchas liming, puering or drenching. For example,'untanned skins,

say one or two such skins, are placed in a drum and enough sodiumhypochlorite solu tion of 33 B. is added to conveniently cover theskins, whereupon the drum is rotated for if about forty-five minutes atroom temperature.

With the ordinary drum about twenty pounds of the sodium hypochloritesolution will be used. The liquid is then drained off and 140 grams ofsodium hydroxide dissolved in twenty 3 pounds of water are added,whereupon the drum is run for fifteen minutes more. The liquid is thendrained and 450' grams of 80%' acetic acid dissolved in twenty pounds ofWater are added, and the drum run until I 35 all the caustic sodapresent is completely neutralized, as determined by a test withphenolphthalein. The liquid is then again drained and the skins pickledand tanned in the usual manner. Such skins after being finished 4 showconsiderable luster but do not compare in sheen with skins lusteredafter the tanning process. There is also a serious objection toApplication filed January 18, 1930. Serial No. 421,808.

. LUSTERI'NG LEATHER ed, and consequently it is desirable to lusterafter the tanning process has been completed.

Sodium hypochlorite may be used for lustering leather when used alone orwith other reagents, but it does not result in the very desirableproduct obtained by the use of my preferred process hereinafterdescribed. l/Vhen leather is treated with sodium hypochlorite solutioncontaining monosodium phosphate in such an amount tha the solution is nolonger alkaline to pheno phthalein indicator, for example, with asolution containing 20% of sodium hypochlorite having 6.5% availablechlorine, and 10% of monosodium phosphate, for thirty minutes, and thendyed and dried out, or when leather is treated with a similar solutionbut containing 10% of ammonium chloride in place of the mono-sodiumphosphate, and then dyed and dried out in the usual manner, a fairlygood product results, but it is not of the same quality as when treatedaccording to'the preferred process.

We have discovered that almost any chlorinating agent will cause somelustering of formaldehyde or chrome tanned leather having 'a nap, suchas suede or mocha leather, al-

though som chlorinating agents have in addition to the lustering effecta more or less undesirable effect of one kind or another, and wetherefore prefer not to use them.

We also discovered that said luster may be produced by treating chrometanned leather with various stripping or detanning agents, such asammonia, sodium diphosphate, sodium triphosphate, sodium tartrate,sodiumcitrate and the like, but the resulting luster is not sufficient forcommercial success.

We have also discovered that available chlorine from substantiallyneutral reagents will give a good lustering effect on leather similarlyto the lusterin efiect on wool as described above, and suc results areespecially good with chrome tanned and formaldehyde tanned leathershaving a'nap such as suede or mocha leather. Various substances may beused as the sourcefor obta ning the chlorine but of all those wehave tred we prefer to use the various organic chlorine compounds such as aredescribed by Chattaway in the Chemical Society Journal (London), 1905,vol. 87, pages 145-171, and of these we prefer the sodium salt ofparatoluenesulphochloramide, also known as Aktivin, since this workseficiently in theprocess and is easily obtainable in commerce. We willhere describe the use of 'Aktivin only, of such compounds, for lusteringleather since the process is essentially the same for all such compoundsexcept the amounts to be used, which can be calculated.

Aktivin is ordinarily neutraland evolves chlorine in contact with otherorganic compounds which are oxidizable, such as wool, cotton and thelike. We obtain some luster by using the Aktivin in amounts from to 5%of the dry weight of the leather, andthe luster is improved by thepresence of an acid, such for example as formic acid, acetic acid,oxalic acid, hydrochloric acid, sulphuric acid and the like.

We have also discovered that a superior luster is obtained by combiningthe step of treating the leather with a detanning agent with the step oftreating it with the chlorinating agent, for example:

l. A tanned shn is treated with a solution containing ammonia in anamount equal to about 5% of the dry weight of the leather,

and ivin in an amount equal to about of the dry weight of the leather,for about a half hour, whereupon it is washed and dyed in the usualmanner.

2. .The process is the same as noted above under No. 11, except that thesolution contains l0% of trisodium phosphate instead of the Men in anamount equal to about 10% of the dry weight of the leather.

3. The skin may be first treated without the Aktivin, that is, with theammonia solution or trisodium phosphate solution or both of thesetogether. After such treatment for one-halfhour the skin is washed, andthen treated in a second bath with a solution containing 10 to ofAktivin and 5% of formic or other organic acid, or 2 to 3% of mineralacid, the percentages stated being likewise based on the dry weight ofthe leather.

Each of these three very beautiful luster.

We have also discovered that an excellent luster is obtained by using amixture of Aktivin d a tanning material in place of the Alrtivin alone;and we prefer to use the synthetic tans-which as a rule are phenol sulphonic acids condensed with aldehydes, very good results being obtainedas ageneral rule with the addition of about two parts of the addedtanning material to t parts of the methods produces a memes Aktivinused. Our preferred method of procedure is to wet back the dry chrome orformaldehyde tanned suede or mocha leather with a wetting out agent,such as a solution of ammonia, sulphonated castor'oil, carbontetrachloride, trichlorethylene, Nekal, the wetting out agent describedin the patent to lPott No. 1,686,836, Uctober 9, 1928, or any othersuitable wetting out agent, together with a detanning agent such asdisodium phosphate, trisodium phosphate, sodium citrate, sodiumtartrate, or ammonia for about twenty to thirty minutes at a temperatureof about 110 to 120 16. As a specific example we may state that poundsof dry leather are placed in an ordinary wooden drum with enough waterto cover the skins at a temperature of 120 F, three pounds of trisodiumphosphate and three pounds of a mixture of about equal parts ofsaponified sulphonated castor oil and trichlorethylene beingadded'thereto, and the drum is then rotated for about thirty minutes,whereupon the skins are washed at to F. for about twenty to thirtyminutes to remove the wetting out agents. At this stage, the leather isin a soft slimy condition. The skins are then treated with an aqueoussolution of Aktivin containing 10 to 15% of Aktivin based on the weightof the dry skins,

enough water being used to cover the skins, and'the solution may not,but preferably does, contain acid as above described, this treat mentbeing preferably at a temperature of 100 to 18. After treating thus forabout ten minutes 4%, that is, four pounds per one hundred pounds of dryskins, of tanning material is added to the solution, and this treatmentis continued for about fortyfive minutes to one hour, preferably at atemperature of 100 to 140 F. The leather is then washed thoroughlypreferably with warm water and dyed in any well known manner. ,Afterdyeing it has the desired luster as well as the desired color, the colorbeing fast to light and washing. It is to be noted that better andquicker results are obtained the higher the temperature of treatment,but it is advisable not to let the temperature ever exceed 140 F, asthis may cause the leather to deteriorate.

Elemental chlorine v and bromine, when used in place of the Aktivin,likewise produce a lustrous effect on the leather.

The lustering treatment not only produces a luster, but it also makesthe leather more receptive to most dyes.

When it is desired to dye the treated leather, this is best done withoutagain drying it, that is, after the last washing step described above.

' To one hundred pounds dry weight of wet leather in a drum we add aboutfive pounds lllti of disodium phosphate, or three pounds of Y trisodiumphosphate, or two pounds of disodium phosphate together with two pounds1 of borax. These substances act to retard the,

aflinity of the dyestuif for the'leather whereby better penetration of,the dye into the drum, the addition of the formic acid re quiring aboutfifteen to twenty minutes, the formic acid acting to overcome theretarding efiect of the sodium phosphate, borax, and the like on theaflinity of the d e for the leather. After all the formic aci has beenadded, rotation of the drum is continued for another twenty minutes,whereupon the leather is washed very thoroughly and dried.

Having thus described the invention, what is claimed as new and desiredto be securedby Letters Patent is: i

1. The process of lustering formaldehyde orchrome tanned suede or mochaleather, which comprises subjecting it to the action of a chlorinatingagent.

2. The process of lustering formaldehyde or chrome tannedsuede or mochaleather, which comprises subjecting it to the action of an organiccompound containing available chlorine.

3. The process of lustering formaldehyde or chrome tanned suede or mochaleather, which comprises subjecting it to the action of Aktivin.

4. The process of lustering formaldehyde or chrome tanned suede or mochaleather, which comprises treating it'with a wetting out agentcontaininga mild detanning agent to soften it and to detandt slightly,washing it, treating it with water containing a chlorinating agent,adding tanning material to said water to neutralize the partialdetanning, and then washing.

5. The process of lustering formaldehyde or chrome tanned suede or mochaleather, which comprises treating it with a wetting out agent containinga mild detanning agent to soften it and to detan it slightly, washingit, treating it with water containing an or-. ganic compound containingavailable chlorine, adding tanning'material to said water to neutralizethe partial detanning, and washing. 7 V

6. The process of lustering formaldehyde or chrome tanned suede or mochaleather, which comprises treatingv it with a wetting out agentcontaining a mild detanning agent to soften it and to detan it slightly,washing it, treating it'with water containing Aktivin,

adding tanning material to 'said'wateito neutralize the partialdetanning, and washing.

1 7. The process of lustering formaldehyde or chrome tanned suede'ormocha leather,

which comprises treating it with a wetting out agent containing a milddetanning agent for about one-half hour at a temperature ofabout 110 to120 F., to soften it and to detan it slightly, washing out said treatlngagents, treating it with water containing ns about '10 to 15% of Aktivinbased on the weight of the dry leather for about ten mmutes, adding tothe treating agent 4%, based on the weight of the dry leather,of'synthetic tanning material containing a sulphonic acid radical,treating the leather therewith for about forty-five minutes, and washingout the reagents. v I

8. .The process of lustering formaldehyde or chrome tanned suede ormocha leather, which comprises treating it with a wetting out agentcontaining a milddetanning agent for about one half hour at atemperature of about 110 to'120 F., to soften it and to detan itslightly, washing out said treatingagents, treating it with watercontaining about 10 to 15% of Aktivin based on the weight of the dryleather for about ten minutes, adding to the treating agent 4%, based onthe weight of the dry leather, of synthetic tanning material containinga sulphonic acid radical, treating the leather therewith for aboutforty-five minutes, washing out the reagents, and dyeing the leather.

9. The process of treating chrome tanned or formaldehyde tanned leatherhaving a nap, which comprises treating it with a chlorinating agent,washing, and dyeing it. 10. The process of treating chrome tanned orformaldehyde tanned leather having a nap, which comprises treating itwith a wetting out agent and a detanning agent, washing it, treating itwith alustering agent, adding a tanning agent to the lustering agent andcontinuing the treatment, and washing it.

11. The process of treating chrome tanned or formaldehyde tanned leatherhaving a nap, which comprises treating it with awetting out agent and adetanning. agent, washing it, treating it with a chlorinating agentcomprising acid, adding a tanning agent to the lustering agent andcontinuing the treatment, and washing it. ,4

12. The process of treating chrome tanned or formaldehyde tanned leatherhaving a nap, which comprises treating it withia wetting out agent and adetanning agent, washing it, treating it with a lustering agent, addinga tanning agent to the chlorinating agent and continuing the treatment,washlng it, and. dyeing it,

. 13. The process of treating chrome tanned or formaldehyde tannedleather having a nap, which comprises treating it with a wetting outagent and a detanning agent, washing it,

. hwittlt treating itwith n ohloninaating agent com-- prising new,adding a tanning agent to the lustering agent and continuing thetreatment 7 Washing it, nnol dyeing it.

v M. A lnstei'edl leather produced by pertielly oletanning the leathersubjecting it to the action of & ohlorineting agent and Iceting it.

15. A lustrous leather protuced by sub- 10 jeoting chrome orformaldehyde tnnnedl leather to the notion of Aktivin.

In testimony whereof we hereunto afix our signatures,

GEQRGE R. PENSEL.

i5 SVEN H. lFRllESTED'l.

